1. Field of the Invention
This invention relates to the inhibition of cavitation-erosion corrosion of aluminum and the corrosion of other metals exposed to an aqueous liquid.
2. Description of the Prior Art
The cavitation erosion-corrosion of aluminum water pumps upon exposure to aqueous systems such as water-cooled internal combustion engine coolants is a relatively new development. While alkali metal molybdates and the soluble salts of tungstic and selenic acids have been used in antifreeze compositions to prevent the corrosion of metals, particularly cast iron, when used in an automobile cooling system, there is no indication in the prior art that soluble salts of molybdic, tungstic and selenic acids act to retard the corrosion of aluminum, particularly the cavitation erosion-corrosion of aluminum water pumps.
Agnew et al in U.S. Pat. No. 3,030,308 disclose an antifreeze composition consisting essentially of a water-soluble liquid alcohol, magnesium metaborate, and an alkali metal molybdate. The antifreeze composition is said to act synergisticly to retard the corrosion of cast iron when used in an automobile cooling system.
Lamprey in U.S. Pat. No. 2,147,409 and Bayes in U.S. Pat. No. 2,147,395 disclose antifreeze compositions comprising an alcohol and a soluble salt of an acid selected from the group consisting of tungstic, selenic and molybdic acids.